Functional significance of aberrantly expressed microRNAs in prostate cancer

Abstract

microRNAs, a class of small non-coding RNAs, regulate protein-coding gene expression by repressing translation or cleaving RNA transcripts in a sequence-specific manner. A growing body of evidence suggests that microRNAs contribute to prostate cancer development, progression and metastasis. Based on reports describing microRNA expression signatures, several differentially expressed microRNAs have been discovered. In the present review, eight genome-wide microRNA expression signatures were used to select aberrantly expressed microRNAs (i.e. upregulated and downregulated microRNAs) in prostate cancer clinical specimens. Also, we mapped these selected microRNAs in the human genome. Interestingly, some clustered microRNAs, such as miR-221/222, miR-143/ 145, miR-23b/27b/24-1 and miR-1/133a, are frequently downregulated in cancer tissues, and recent studies have shown that these clustered microRNAs function as tumor suppressors. We also discuss the functional significance of the differentially expressed microRNAs and the molecular pathways/targets regulated by these microRNAs. These recent findings of microRNAs in prostate cancer will facilitate the development of effective strategies for microRNA-based therapeutics for the treatment of prostate cancer.

Recent trends in microRNA research into breast cancer with particular focus on the associations between microRNAs and intrinsic subtypes

“…133,134 Cancer stem cell-related miRNA Recent studies have suggested that miRNA contribute to tumor initiation by regulating the properties of CSC, including their selfrenewal, de-differentiation and drug resistance. 5,9,135 Han et al 136 demonstrated that the formation of CSC-like cells that were undergoing EMT was associated with the overexpression of hypoxiainducible factor 1α and that this process was regulated by miR-21. Let-7 has an important role to regulate the function of CSC, because the reduction of let-7 expression inhibits differentiation and maintains proliferation.…”

“…1 On the other hand, microRNAs (miRNAs) are small (19-22 bases in length) non-coding RNAs, and negatively regulate protein-coding gene expressions by promotion of mRNA degradation or inhibition of translation. 5 In breast cancer, various miRNAs have been shown to be deleted or to exhibit downregulated or upregulated expression. Recently, it has been demonstrated that aberrational miRNAs targeting to several cancer-related genes induce cancer initiation, progression, metastasis or drug resistance.…”

“…On the other hand, reduction or loss of expression of tumor-suppressive miRNAs induce upregulated expression of their target oncogenes. 5 In breast cancer, a number of miRNAs have been found to have oncogenic or tumor-suppressive effects, and miRNAs have important roles in tumor initiation, drug resistance and metastasis. [6][7][8][9][10][11] The function of miRNAs associated with tumor development in breast cancer are shown in Table 2.…”

MicroRNA‑138 suppresses cell proliferation and invasion of renal cell carcinoma by directly targeting SOX9

“…It is estimated that >30% of human genes are regulated by miRNAs, and that they are involved in a variety of biological functions, including proliferation, differentiation, cell cycle, apoptosis, angiogenesis, invasion and metastasis (13,14). An accumulating number of studies have reported that miRNA expression levels are dysregulated in a variety of human cancer types (15)(16)(17). miRNAs play key functions in the initiation and progression of tumors by serving as oncogenes or tumor suppressors, primarily depending on the roles of their target genes (18)(19)(20).…”

Regulation of HMGB3 by antitumor miR-205-5p inhibits cancer cell aggressiveness and is involved in prostate cancer pathogenesis

“…In contrast, downregulated antitumor miRNAs can lead to overexpression or activation of oncogenes. Discovery of microRNA (miRNA)-regulated genes improves our understanding RNA networks in cancer cells [9][10][11][12][13][14][15].…”